Chelating phosphine compounds when bound to metal atoms are generally known to be useful as catalysts. One reaction which uses palladium phosphine catalysts is the coupling of aryl halides with amines for the production of arylamines, as reviewed by Hartwig, SYNLETT, 1997, (4), pg. 329-340. An example of this reaction is the coupling of chlorobenzene and piperidine to form N-phenylpiperidine: ##STR1##
Another reaction in which palladium/phosphine catalysts have been used is the Suzuki reaction, where biaryls are produced through the coupling of arylboronic acids and aryl halides, as reviewed by Suzuki, A, J. Orgmet. Chem., 576 (1999), pg. 147. One example of this reaction is the preparation of biphenyl from phenylboronic acid and chlorobenzene: ##STR2##
Both of these products are important classes of compounds widely used in the manufacture of pharmaceuticals, advanced materials, liquid polymers and ligands, and much work has been done on their preparation. However, there is an expanding need for stable, easily prepared catalysts that result in good yields and mild reaction conditions.
Preparation of new ligands has traditionally been performed one at a time after tedious synthesis and purification protocols. Combinatorial techniques have greatly accelerated the discovery of new ligands, but new synthetic schemes are needed. One valuable technique uses solid-phase supports. This solid-phase protocol allows reactions on a polymer-bound scaffold to be driven to completion by using large excesses of reagents in solution that can be easily filtered away from the polymer support. After the scaffold has been modified, an additional cleavage step then frees the small molecule from the polymer support into solution for isolation.
Phosphine oxide compounds and libraries have been prepared using polymer scaffolds in U.S. application Ser. No. 09/415,347 (U.S. Ser. No. 99/23509) which is incorporated in its entirety by reference. Lacking is a process for the convenient preparation of stable arylamines of the formula R.sup.1 --NR.sup.2 R.sup.3 or biaryls of the formula R.sup.1 -R.sup.6 using a stable phosphine catalyst under mild conditions and producing good yields.